From: Sean Christopherson <[email protected]> Zap only leaf SPTEs when deleting/moving a memslot by default, and add a module param to allow reverting to the old behavior of zapping all SPTEs at all levels and memslots when any memslot is updated.
Signed-off-by: Sean Christopherson <[email protected]> --- arch/x86/kvm/mmu/mmu.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 1f96adff8dc4..3c7e43e12513 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -84,6 +84,9 @@ __MODULE_PARM_TYPE(nx_huge_pages_recovery_ratio, "uint"); static bool __read_mostly force_flush_and_sync_on_reuse; module_param_named(flush_on_reuse, force_flush_and_sync_on_reuse, bool, 0644); +static bool __read_mostly memslot_update_zap_all; +module_param(memslot_update_zap_all, bool, 0444); + /* * When setting this variable to true it enables Two-Dimensional-Paging * where the hardware walks 2 page tables: @@ -5441,11 +5444,26 @@ static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm) return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages)); } +static void kvm_mmu_zap_memslot(struct kvm *kvm, struct kvm_memory_slot *slot) +{ + /* + * Zapping non-leaf SPTEs, a.k.a. not-last SPTEs, isn't required, worst + * case scenario we'll have unused shadow pages lying around until they + * are recycled due to age or when the VM is destroyed. + */ + spin_lock(&kvm->mmu_lock); + slot_handle_all_level(kvm, slot, kvm_zap_rmapp, true); + spin_unlock(&kvm->mmu_lock); +} + static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm, struct kvm_memory_slot *slot, struct kvm_page_track_notifier_node *node) { - kvm_mmu_zap_all_fast(kvm); + if (memslot_update_zap_all) + kvm_mmu_zap_all_fast(kvm); + else + kvm_mmu_zap_memslot(kvm, slot); } void kvm_mmu_init_vm(struct kvm *kvm) -- 2.17.1
